Telephone system



March 10, 1925. 1,529,419

G. A. BETULANDER TELEPHONE SYSTEM FiledMarch 1, 1923 4 Sheets-Sheet 1 Mmb 10. 1925.

G. A. BETULANDER TELEPHQNE SYSTEM Filed Lurch 1, 1923 w 4 Sheets-Sheet 2 March 10, 1925. 1529.419

G. A. BETULANDER TELEPHONE SYSTEM Filed March 1, 1923 4 Sheets-Sheet s FIG- Much to, 1925. 1,529,419

- G. A. BETULANDER TELEPHONE SYSTEM Filed March 1, 1923 4 Sheets-Sheet 4 W%7&W y @M Patented Mar. 10, 1925.

UNITED ST TES PATENT OFF'IGE'.

GOTTHILF ANSGARIUS BETULANDER, OF STO'CKIHOLEE,SVIEDEN, ASSIGNOR 'IQTHE RE- LAY AUTOlvIATIO TELEPHONE COIYTPANY, LIMITED, 033 LONDON,,ENGLA ND.

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Application filed March 1, 1923. Serial No. 622,090.

ing divisions, in which the selection of a:

disengaged outgoing junction line is eii ected by means of a number oi non-numerical selectors or so called searchers (otherwise known as master switches) which are separate from the connecting apparatus, and accessible in common to the incoming lines. In some systems ot' this kind, particularly those in which the connections are estab lished by means of relays, means have been provided for preventing double connections and confusion of lines, by which means when there are several simultaneous calls, the different calls in each particular switch ing division become effective insuccession, so that only one calling line can. obtain connection at a time, in which case, therefore, only one searcher .is required for each switching division. This arrangement, h0wever, has the disadvantage that a whole switching division and, consequently, also all incoming lines of the division may be blocked by faults in said common switching apparatus. When grouping the lines in large groups it therefore becomes a practical necessity to provide means which, while allowing simultaneous connection of several calling lines in the same switching division, will prevent double connections;

This is attained according to the present invention by putting the marking of the dif- :ierent lines in the connecting apparatus under the control of the searchers, of which inthis case there are several in each switching division, so that, when there are simultaneous calls, the lines to be connected will be marked simultaneously and separately in different connecting apparatus.

The invention is illustrated by the accompanying drawings, in which Figs. 1, 2 and 3 illustrate schematically the principle of ers being, however, shown in thesenlatter figures.

Fig. 1. shows schematically a switching di vision comprising a number otinconhing linesIL and a. numberof outgoing lines UL. The circles at the points of intersection out. these lines indicate the connecting possibilities and the rectangles AK indicatathe connecting apparatus, which in the example; shown are supposed to be assigned tothe outgoing lines, that each outgoingline may obtain by means of an appertaining-apparatus connection with any one of: the incoming lines. The connecting apparatusmay, hovever', be allotted to the incoming lines. The particular construction. of the connecting apparatus is unessentia-l, forthe present purpose.

The incoming lines IL are provided, with a number of searchers S S accessible in common to the incoming lines, two; of said searchers being shown in Fig; 1, each being adapted to select a disengaged-v outgoing line UL. According to the invention these searchers are also arranged to. control the marking of the calling lines in the connecting apparatus AK, so that the calling; line will be marked only in that connecting-apparatus which belonos to the outgoing line selected by the searcher, tor the purpose of preventing double connections, whenseveral calls occur simultaneously. If there were no such control double connections could occur for instance by two; simultaneously calling incoming lines being connected to the same outgoing line in the same connecting apparatus or by two outgoing lines being connected to the same incoming line in different connecting apparatus. This is now prevented by putting the circuits, whereby the lines are marked in theconnecting a iparatus, under the control of the searchers, so that they may be switched by the latter to any one of the connecting apparatus. As shown in Fig. 1, each searcher is arranged to control a separate group of marking circuits M53 M8,, by means of relays GB GR, or the like, through which each group of circuits can be switched on to any of the connecting apparatus AK.

Each group of marking circuits is further put under the control of a call sequence controller, OK and OK respectively, consisting of relays adapted to control said circuits for the purpose of marking the calling line in question, said controllers being also arranged to effect such a control of the circuits as to prevent a simultaneous marking of more than one calling line in each group MS or M5 so that, in case several calls occur simultaneously, the calls will be marked one after the other according as the searcher becomes available for another call.

The switching operation proceeds principally in the following manner. On a call occurring on one of the incoming lines, one of the searchers S is immediately operated to select a disengaged outgoing line and to connect the appertaining group of marking circuits MS to the connecting apparatus A'K corresponding to the line selected, by operating the corresponding relay GR. At the same timethe calling line has been marked by the corresponding call sequence controller OK and the connecting apparatus Will therefore be operated in such a manner that the outgoing line selected is connected to the incoming line in question. In case two calls should occur simultaneously the two searchers are operated each by one calling line and the searchers will therefore be operated simultaneously. Supposing the searchers then select different outgoing lines, the calling lines will be marked in the different connecting apparatus corre sponding to the difierent selected outgoing lines, as described, and consequently, they will obtain connection each with a separate outgoing line. If, on the other hand, the searchers should be operated exactly at the same moment so as to select the same outgoing line, the searchers would also operate the corresponding relays GR and GB, at the same time. In order to prevent a double connection in such a case the two relays GR Grit of each pair of relays corresponding to each particular connecting apparatus AK are so combined with one another that, in case they are operated simultaneously, only one of them can be brought into operation. The two calling lines will therefore obtain connection one after the other. As soon as one of the calling lines has been connected to the outgoing line in question, the latter will be marked as engaged and the second searcher will then immediately search for the next disengaged line and effect the connection of this line with the second calling line. I

In order to reduce the probability of the searchers selecting the same line, the Search ers may be connected so as to select the outgoing lines in a different order of sequence, as shown in Fig. 2, wherein the outgoing lines are connected to the searchers in a re versed order of sequence, so that the Searcher S selects the lines in the order UL IIL UL whereas the searcher S selects the lines in the order UL UL UL It is readily seen, that the case above referred to, when both searchers select the same line, can occur in the arrangement according to Fig. 2 only in the rare case when the searchers are operated simultaneously, while all outgoing lines except one are engaged.

According to Fig. 2 the incoming lines are further divided into two groups G G provided each with a separate searcher S and S respectively, so that the lines of the group G, are capable of operating only the searcher 3,, whereas the searcher S can be operated only by the lines of the group G This arrangement has the advantage that the wiring of the searchers S and the call sequence controllers OK is simplified and, in addition thereto, the possibility of a complete block- I ing of the switching division is further reduced. I

Fig. 3 shows the arrangement according to Fig. 2 applied to switching divisions having more than two searchers. The searchers are then likewise connected so as to select the outgoing lines in a different order of sequence, but the lines UL are screwed in respect of their connection to the searchers, as shown in the drawing. The arrangement according to Figure 3 is obviously not so good as that of Figure 2, as, although the possibility of two searchers landing on the same UL line is reduced it is not eliminated if the first two lines over which the searchers search should be busy.

The invention is primarily suitable for the preselecting and group selecting stages of automatic and semi-automatic telephone eX- changes, but it may generally be applied to switching systems of all kinds where connection is to be established with any one of a number of switching apparatus or the like, for instance number registers, operators positions etc., which are accessible in common to a plurality of lines.

Figs. 4 and 4 show two groups G G of incoming lines IL and two outgoing lines UL UL with appertaining connecting apparatus AK AK A suitable type of connecting apparatus consists of a number of marking relays MR and a number of connecting relays AR, adapted to be operated two by two in different combinations. The sets of contacts KG are arranged in intersecting (horizontal and vertical) rows, one marking relay MR being provided for each vertical row and one connecting relay AR for each horizontal row. The arrangement is such that the set of contacts KG desired will be operated by energizing the relays MR, AR of the corresponding vertical and horizontal rows.

- operated by energizing the relays MR and The sets of contacts KG of each apparatus AK are connected partly parallelly with the corresponding outgoing line UL and partly with the different incoming lines IL. In the example shown each group G, and G respectively of incoming lines comprises the lines connected to two vertical rows. The lines connected to the different vertical rows form sub-groups UG,, UG,. Each connecting apparatus comprises 100 sets of contacts arranged in ten rows. Thus, each sub-group U'G would comprise ten lines but other ways of grouping the lines and the sets of contacts are, obviously, possible.

Assigned to each group G, and G respectively is a call sequence controller, which consists in this case of a number of relays BR corresponding to the different vertical rows or sub-groups UG, and a number of relays CR corresponding to the different lines,

of each vertical row or sub-group UG.

Fig. 5 shows the searchers S, and S, belonging to the line groups G, and G, as well. as the relays GR by means of which the marking circuits MS, and M8 are switched on to the different connecting apparatus AK. The switching operation is as follows Upon a call for instance on the line IL, a circuit 1 is closed through a relay LR,, which then closes a circuit 2 through the relay BR, of the corresponding sub-group UG,. The relay last mentioned then energizes and connects itself into a holding circuit 3 carried over a back contact of the relay BR, and including the relay DR, which, upon energizing, closes a circuit A through the relay CR, corresponding to the line IL,. The latter relay then connects itself into a holding circuit including the relay DE A call occurring later in the subgroup UG cannot disturb the switching operation thus started, as the circuit of the relay BR is open at the relay DR,, and consequently, said call cannot be eii'ective until the first switching operation is completed. In case calls should occur in both sub-groups UG, and UG so that the relays BR, and BB, are operated simultaneously, the relay BR, would open the holding circuit of the relay BR, and, consequently, even in this case only one of the calls would be effective, while the other will have no effect, until the operation started has been completed. In case two or more calls should occur simultaneously within the same sub-group, only one of the relays CR would be brought into operation or retained in operated position. owing to the relays CR controlling mutually their holding circuits similarly to the relays BR. The effect of the relays BR and GR is therefore that, in case of several calls occurring simul taneously within the group Gr in question,

only one of the calling lines will be marked as calling and obtain connection, while the other will have to wait, until the line first marked has obtained connection, when one of the waiting lines is immediately marked in a similar way.

Upon the energizing of the relay DR,, a circuit 6 was completed which, on the sup position ofthe first outgoing line UL, beingdisengaged, is closed through the first relay SR, of the searcher S,. The relay last mentioned now closes a circuit 7 through therelay G,R, which then switches the'marking circuits MS, on to the operating apparatus AK, at the same time connecting itself into a holding circuit containing a relay HR which by opening a contact k'preventsasuh sequent energizing of the relay G R for the purpose of obviating disturbances by calls from the group G,. Similarly upon a call in the group G the relay G,R, would prevent disturbance by calls from the group G, by cutting in the relay HR If, on account of simultaneous calls-from both groups G, and G both relays G,R, and G,R, should be cut in simultaneously, only the relay G,R would remain operated, as this re lay opens the holding circuit of the relay G,R,. In this way a simultaneous marking of a plurality of calling lines in the same connecting apparatus is prevented in case of the searcher selecting the same outgoing line.

Upon the marking circuits MS, being switched on to the connecting apparatus a circuit 8 is closed through the marking relay MR,, which then closes a circuit 9 through the operating winding AL of the connecting relay AR The relay last mentioned, upon energizing, operates the sets of contacts KG,, whereby the line IL, is connected to the line UL,. At the same time a holding circuit 10 is closed through the holding winding HL of the relay AR and a cut-off relay UL,. The latter relay cuts ofi' the relay LR, thereby causing a successive de'energizing of the relays used for the switching operation, except the connecting relay AR which maintains the connection, until the connection is severed at the end of the conversation. Upon the operation of the relay AR a circuit ll is closed through a relay FR,, whereby the line UL, is marked as engaged.

What I claim is 1. In a telephone system, the combination with a group of lines and a group of switches, each switch being adapted to connect to any one of the lines, of a plurality of devices common to the group of switches and adapted to mark a calling line in only one of the switches and to mark that switch in which the line is so marked.

2. In a telephone system, the combination with two groups of lines and a group of switches, each switch being adapted to connect to any one of the lines of either group,

of a plurality of devices adapted, when a line in each group calls simultaneously, to mark two simultaneously calling lines in two different switches and to mark those two switches individually to the two lines.

3. In a telephone system, the combination with a group of lines and a group of switches, each switch being adapted to connect to any one of the lines, of a plurality of devices, each consisting of a master switch adapted to mark a switch as the one to connect to a calling line and of a sequence controller adapted to mark only one line as calling in the switch so marked.

4. In a telephone system, the combination with a group of lines and a group of switches, each switch being adapted to conmeet to any one of the lines, of a plurality of devices, each consisting of a master switch adapted to mark a switch as the one to connect to a calling line, a sequence controller adapted to mark only one line as calling in the switch so marked and means for temporarily preventing the sequence controller from marking if two master switches are marking the same switch of the group and thereafter for permitting the master switch associated with the sequence controller which was temporarily prevented from marking to mark another switch of the group.

5. In a telephone system, the combination with a group of lines and a group of switches, each switch being adapted to connect to any one of the lines, of a plurality of devices, each consisting of a master switch, each of the master switches being adapted to choose in a different order of sequence one of the switches of the group and to mark that one as the one to connect to a calling line, a sequence controller adapted to mark only one line as calling in the switch so marked and means for temporarily preventing the sequence controller from marking if two master switches are marking the same switch of the group and thereafter for permitting the master switch associated with the sequence controller which was temporarily prevented from marking to mark another switch of the group.

6. The combination with a group of lines divided into sub-groups and a group of switches adapted to connect to any line of the group, of a plurality of devices, each device consisting of a master switch adapted to mark any idle switch of the group as the one to connect to a calling line and of a sequence controller associated with one of the sub-groups and adapted to mark only one line as a calling line in the switch marked by the master switch.

In testimony that I claim the foregoing as my invention I have signed my name this 2nd day of February 1923.

GOTTHILF ANSGARIUS BETULANDER. 

